I do think some of these policies are really restrictive, and there are definitely some SEN children who will not cope within this system, but there are more children (SEN and not) who will benefit.
I am always shocked and disgusted with the amount of bad behaviour that is excused, allowed, supported etc.. in some schools. Not every badly behaved child has SEN, and not every SEN child is unable to control their behaviour. Excusing poor behaviour by using a SEN label is doing a disservice to the child, because it tells them you don't expect them to be better, to achieve anything, to be successful. Letting a child do what they want and not requiring they learn, attend, respect staff and other children, is not doing what's best for that child.
Schools have got to have standards, and people not able to, or not willing to, meet those standards should not ruin things for everyone else. Class time should not be spent with teachers debating with pupils over basic respect. Or having to manage one child who is taking up 90% of the class time and attention.
Rules like this don't mean the teachers don't care, they just care equally about everyone and think that all the children have an equal right to time, attention, and education.